Problem-1- Answer the following questions ;

1. A race car’s forward velocity increases from 4.0 m/s to 36 m/s over a 4.0-s time interval. What is its average acceleration?

2. The race car in the previous problem slows from 36 m/s to 15 m/s over 3.0 s. What is its average acceleration?

3. A bus is moving west at 25 m/s when the driver steps on the brakes and brings the bus to a stop in 3.0 s. What is the average acceleration of the bus while braking?

4. How long does it take for a car to brake from 25 m/s to 16 m/s at a constant acceleration of 3m/s2? Assume that the forward direction is positive

Fatima Alsawafteh AUHS-G Mon/21th/Jan/2013

Grade 9 - PHY-100

Problem-2- Rank the following objects according to the magnitude of the acceleration, from least to greatest. Specifically indicate any ties.

A. A falling acorn accelerates from 0.50 m/s to 10.3 m/s in 1.0 s.

B. A car accelerates from 20 m/s to rest in 1.0 s.

C. A centipede accelerates from 0.40 cm/s to 2.0 cm/s in 0.50 s.

D. While being hit, a golf ball accelerates from rest to 4.3 m/s in 0.40 s.

E. A jogger accelerates from 2.0 m/s to 1.0 m/s in 8.3 s.

Problem -3- Use The table below that shows the velocity of a student walking down the hallway between classes to answer a, b, c :

a. What is happening to the student’s speed during

t 60.0 s and t 61.0 s?

b. What is his acceleration between t 10.0 s and t 20.0 s?

c. What is his acceleration between t 60.0 s and t 61.0 s?

Problem- 4 -

a. Give an example of each of the following:

1. an object that is slowing down but has a positive acceleration

2. an object that is speeding up but has a negative acceleration

b. Explain Why the orbits accelerated when rotating around the earth, although its speed is constant.

Fatima Alsawafteh AUHS-G Mon/21th/Jan/2013

Time (s) Velocity (m/s)

0.0 0.0

10.0 1.5

20.0 1.5

30.0 1.5

31.0 0.0

40.0 0.0

50.0 3.0

60.0 3.0

61.0 0.0

Problem – 5 - The driver of a car traveling at 30m/s slams on the brakes so that the car undergoes a constant acceleration, skidding to a complete stop in 4.5 s .

(a) What is the average acceleration of the car during braking?

a. 0.041 m/s2 c. 6.8 m/s2

b. 0.15 m/s2 d. 24 m/s2

(b) Which is the most accurate plot of velocity versus time for the braking car?

a. c.

b. d.

Fatima Alsawafteh AUHS-G Mon/21th/Jan/2013

Problem -6- A 0.250-kg cart moves on a straight horizontal track. The graph of velocity, v, versus time, t, for the motion of the cart is given below.

Time interval (s) (0.0 – 5.0) (5.0-8.0) (8.0 – 13) (13 –17) (17-23)

The car is accelerated in the negative direction.

The car is accelerated in the positive direction

The car is moving with constant velocity

a. Use the data of the graph to click the suitable answer (put ✓):

b. Compare the magnitude of the average acceleration of the car between the first two seconds and the final two seconds. Explain your answer using calculations.

Fatima Alsawafteh AUHS-G Mon/21th/Jan/2013

Problem 7: Complete the following map using the following expressions:

Problem 8: Circle the letter of the choice that best completes the statement or answers the question.

1. The slope of a tangent line on a velocity-time graph is the . displacement average acceleration velocity

Fatima Alsawafteh AUHS-G Mon/21th/Jan/2013

applying brakes

A car moving with constant velocity

Motion

Moving with constant velocity – moving with changing velocity – uniform motion – non uniform motion – speeding up- slowing down – sliding – a car moving to the north with constant speed.

acceleration due to gravity

2. When acceleration and velocity vectors are pointing in opposite directions, the object is . speeding up moving at constant speed slowing down not moving 3. If a runner accelerates from 2 m/s to 3 m/s in 4 s, her average acceleration is .

4.0 m/s2 0.40 m/s2 2.5 m/s2 0.25 m/s2

4. __________ means that equal displacements occur during successive equal time interval Average speedUniform motionAverage accelerationUniform acceleration

5. A car with a velocity of 30 m/s accelerates uniformly at the rate of 2.0 m/s2 for 10 s. What is its final velocity?

50 m/s2

40 m/s2

40 m/s50 m/s

6. How long will it take an airplane at rest that accelerates uniformly at 2.5 m/s2 to reach the ground velocity of 2.0×102m/s that is required for take off?

28 s35 s11 s80 s

7. A car accelerates uniformly at a rate of 0.50 m/s2 for 1.0×101 s. Its final velocity is 23 m/s. What is the initial velocity?

18 m/s2

28 m/s28 m/s2

18 m/s

Fatima Alsawafteh AUHS-G Mon/21th/Jan/2013

8. The slope of the line tangent to the curve on a velocity-time graph at a specific instant of time is the __________. average velocity instantaneous velocity instantaneous acceleration displacement

9. 4. A car moving north at 80 km/h turns and travels south at 65 km/h. What are the magnitude and direction of the change in velocity? 145 km/h, south to north 145 km/h, north to south 25 km/h, north to south 25 km/h, south to north

10. The graph in below describes the motion of two bicyclists, Ahmad(A) and Brain(B), who start from rest and travel north, increasing their speed with a constant acceleration. Which of the following is true during the time shown for each?

Ahmad acceleration is greater than Brain acceleration. Ahmad acceleration is less than Brain acceleration. Both Ahmad and Brain have the same acceleration. Both Ahmad and Brain have no acceleration.

11. The graph below shows the motion diagram of a moving car.:

Fatima Alsawafteh AUHS-G Mon/21th/Jan/2013

Which of the following represent both the velocity and acceleration vectors for this car:

( ) ( ) ( ) ( )

Fatima Alsawafteh AUHS-G Mon/21th/Jan/2013